In the application of caulking compounds and other viscous materials, widespread use is made of caulking guns. Caulking guns as such are well known in the art and widely used. The most common caulking guns fall into one of two general classifications.
The first type is a B-D gun or a bulk dispensing gun which is a complete unit unto itself, containing a closed cylindrical chamber or shell with nozzle and actuating means.
The second type of commonly used caulking gun is one that has an open framed supporting structure with an actuating mechanism, and is designed to accept a separate disposable cartridge that has its own nozzle. The open framed cartridge gun (C-gun) essentially comprises two separate elements, i.e., the caulking gun being the first element, and the cartridge and its nozzle being a second separate and disposable element. The present invention is concerned primarily with the C-gun type caulking gun, and in the following discussion the term "caulking gun" should be understood as referring to the second or C-gun type.
Typically, caulking guns are constructed to provide a cradle to receive a cartridge containing caulking compound. The cartridge has a dispensing nozzle at one end and a piston within it which can be urged against the compound via displacement of a push rod and thrust disk associated with the caulking gun. These cartridges are approximately 2-3 inches in diameter and about 8-12 inches in length.
The caulking gun has an open framed or cradle into which the caulk cartridge can be introduced, and a reciprocating stem or push rod having a thrust disk at the front end. The thrust disk can be urged against the caulk cartridge piston which in turn acts to force caulking compound out of the cartridge nozzle. Typically, the push rod is actuatable by a manual lever or trigger which actuates a driving pawl or dog which reciprocates in step as the trigger is manipulated.
Many attempts have been made to improve caulking guns. See, for example, U.S. Pat. No. 1,986,166 which discloses a caulking gun with an outboard rearwardly mounted plunger release and a forward trigger pivoted below the plunger shaft drive grip. U.S. Pat. No 2,530,359 discloses a caulking gun with forward trigger pivoted below the plunger shaft drive grip and forward release.
U.S. Pat. No 2,561,825 discloses a caulking gun with forward trigger pivoted below the plunger shaft drive grip and plunger shaft release having a substantially horizontal control lever above the plunger shaft. U.S. Pat. No. 4,213,546 shows a caulking gun with an improved cap for the cartridge nozzle, and U.S. Pat. No. 4,135,644 shows such a caulking gun having a cartridge nozzle cutting hole in its handle and also having a cartridge puncturing tool retractably mounted in its handle.
U.S. Pat. No. 3,726,440 teaches a caulking gun with a telescopic tubular casing for holding a caulk cartridge. The caulking gun can be provided with an extension member and be telescoped out to a greater length so as to reach distant areas.
Further reference may be made to U.S. Pat. No. 5,137,184; U.S. Pat. No. 4,258,884; U.S. Pat. No. 3,726,440; U.S. Pat. No. 5,017,113; U.S. Pat. No. 3,651,994; U.S. Pat. No. 5,188,259; and U.S. Pat. No. 3,774,816.
A readily apparent common feature in all these devices is the requirement for a push rod which is hand jacked to push the movable piston within the essentially rigid and round caulk cartridge. Obviously, in order for the push rod to be able to urge the thrust disk along the entire length of the cartridge, the push rod must be at least as long as the cartridge, plus the length of the path through the pistol grip which the push rod must travel. In addition, a small segment of the push rod must remain exposed after the cartridge has been depleted, so that the exposed segment of the push rod can be grasped by hand, rotated to disengage from the ratcheting pawls, and retracted to the starting position.
It can thus be readily calculated that, for a cartridge length of 8 inches, the push rod may be 12 inches in length. Assuming a further two inches of nozzle length, it becomes apparent that the total length of the caulking gun, at the time the caulking tube is full, is approximately 23 inches. Such caulking guns are awkward and cannot fit into tight spaces such as cupboards, closets, behind doors, in attics, in boats, etc.
While a wide variety of improvements have been proposed for caulking guns, no improvements have been proposed which would solve the problem of access to tight spaces.
It is an object of the present invention to provide a caulking gun which is makes use of conventional cartridges, yet permits access to tight spaces.